The evolution of integrated circuits has been to decrease the package size of an integrated circuit while increasing the number of electrical leads for electrical interconnection between the integrated circuit and a circuit board on which it resides. As the number of electrical leads per integrated circuit has increased, the electrical leads have become smaller in size and more closely spaced, thereby increasing the difficulty in mounting an integrated circuit to a circuit board.
One method of overcoming this difficulty has been to replace the electrical leads, which are located around the perimeter of an integrated circuit package, with electrical contacts, which are located on the bottom surface of an integrated circuit package, thereby forming a leadless integrated circuit package. These electrical contacts typically have the shape of small protuberances or "balls" which are spaced in a grid array pattern. An integrated circuit package having these bottom surface electrical contacts is placed within a leadless integrated circuit socket or mounting device which retains the integrated circuit package. The mounting device has mating electrical contacts spaced in a grid array pattern which align with the electrical contacts on the integrated circuit package so as to provide electrical continuity between the integrated circuit package and a circuit board upon which the mounting device resides.
One problem that arises with leadless integrated circuit packages is that the electrical contacts of a leadless integrated circuit package and the mating electrical contacts of a mounting device become oxidized, which results in increased contact resistance and therefore decreased conduction between the electrical contacts of the integrated circuit package and the mating electrical contacts of the mounting device. The insertion force used to place a leadless integrated circuit package into a mounting device typically removes some of this oxide, thereby providing improved electrical contact. However, leadless integrated circuit packages are typically not inserted into a mounting device in a manner that is conducive to the removal of oxide on the electrical contacts, and since leadless integrated circuit packages are not directly soldered to the mounting device, the accumulation of oxide on the electrical contacts can result in poor electrical contact.
Another problem that arises with the use of leadless integrated circuit packages is that the electrical contacts of a mounting device are typically electrically connected to electrical leads which are soldered directly to a circuit board. The mounting device must therefore be desoldered if replacement or removal is required. As is commonly known in the industry, repeated soldering and desoldering typically degrades the quality of a circuit board, usually to the point where replacement is required. Thus, a solderless electrical connection scheme would be desirable.
In the fabrication of electronic or electrical devices and circuits, conductive paths and contact areas are usually provided by chemical etching and photolithographic techniques such as in the fabrication of printed circuit boards, and by plating techniques whereby one or more metal layers are provided on, for example, electrical contacts or contact areas of circuit boards, electrical devices, and the like. Such fabrication techniques are well known and are widely employed. They do, however, require a number of process steps and specialized fabrication equipment which adds to the cost and complexity of the manufacturing process and of the resultant products. Thus, the discovery of simpler fabrication techniques would be desirable.